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The Balance of the Environment
   The balance of the environment can be
    upset by the way in which humans obtain
    and use natural resources. If humans use
    renewable natural resources faster than
    they can be replaced, the balance will be
    upset. If we damage one resource in the
    process of obtaining or using another
    resource, the balance will be upset.
   Pollution is the release into the
    environment of substances that change
    the environment for the worse. Most
    pollution is the result of human activities.
The Trail of Pollution
   In order to make a can of soda, the aluminum
    must be removed from the ground. Digging
    scars the land. Chemicals used in the factory to
    produce aluminum become waste that is
    discarded and ends up in a river as pollutants.
    The fuel burned to to make the aluminum into a
    can produces smoke that pollutes the air. The
    process used to make the soda to go into the
    can also produces pollutants. The consumer
    buying the can disposes of it as litter, another
    form of pollution.
Sources and Solutions
   A great amount of pollution is tied directly to
    energy use. The world’s heavy dependence on
    fossil fuels has made pollution a major concern.
    The activities involved in finding and using fossil
    fuels have led to land, air and water pollution.
   Solutions can involve new ways to regulate and
    reuse materials. Solutions can also involve
    alternative energy to replace fossil fuels.
Main Types of Pollution
   Land
   Air
   Water
Land Pollution
Land Pollution
   Most of the energy (90%) used comes
    form fossil fuels. Solar, wind, water and
    other alternative energy resources
    account for only 5%. Nuclear energy
    accounts for the other 5%. Obtaining both
    fossil fuels and nuclear energy can pollute
    the Earth.
   The use of coal was an important step in
    the industrialization of the United States.
    Coal near the surface is strip mined. This
    process badly damages the land and
    causes soil and land pollution. Fertile
    topsoil is buried under tons of rock. When
    the rock is exposed to precipitation, acids
    and other harmful chemical seep into the
    ground, polluting the soil and land.
Hazardous Wastes
   Wastes from factories may pollute the land
    with toxic chemicals, called hazardous
    wastes. Hazardous wastes can cause
    death or serious damage to human health.
    Factories that produce fuels and
    petrochemicals from petroleum are the
    major sources of hazardous waste. When
    improperly stored in barrels buried in
    dumps, the wastes seep into the soil.
Management of Hazardous
   The best solution is to produce less
    hazardous wastes.
   In some cases, industries can reuse the
   Other wastes might be chemically treated
    to change the toxic substances they
    contain into nontoxic substances.
Radioactive Wastes
   Radioactive wastes are the wastes
    produced as a result of the production of
    energy in nuclear power plants.
    Radioactive wastes are classified as either
    high-level or low-level. High-level wastes
    are primarily the used fuel rods from a
    nuclear reactor. Low-level wastes may
    include contaminated equipment used in
    the power plant.
Disposing of Radioactive Wastes
   Low-level wastes decay quickly. High-
    level wastes may of half-lives of 10,000
    years or more. Isolating them from the
    environment for that length of time is
    almost impossible. In the past, high-level
    wastes were sealed in concrete or glass
    containers. The containers usually began
    to corrode or leak.
New Method of Disposal
   A new method of disposal has been
    proposed. Wastes can be buried in rock
    formations that are not subject to
    movement of in salt mines. This is known
    as Geologic disposal. Disposal in ocean
    beds is another alternative. Some
    scientists have suggested shooting
    rockets carrying high-level wastes into the
Solid Wastes
   Americans produce about 11 billion tons of
    solid wastes every year. Solid wastes are
    useless, unwanted or discarded materials.
    They include agricultural wastes,
    commercial and industrial wastes and
    household wastes. Another word for solid
    waste is garbage. Mountains of garbage
    once surrounded cities.
Sanitary Landfills
   One way to deal with solid waste dumps is
    to cover them with thick layers of soil. In
    1976 the United States Congress
    prohibited open dumps. They ruled that
    all existing open dumps were to be
    converted to sanitary landfills. All garbage
    is compacted and covered at least once a
    day with a layer of soil. Once filled they
    can be used as parks.
Problems with Landfills
   A problem with sanitary landfills is that
    when compacted garbage begins to
    decompose and methane gas is produced.
    It burns easily and is a fire hazard. Gas
    wells need to be installed. Wastes can
    ooze out of landfills and pollute the
    surrounding soil. The biggest problem is
    finding a place to put them.
Ocean Dumping
   At one time, solid wastes were commonly
    towed offshore and dumped into the
    ocean. Much of the debris has washed up
    on beaches. Today some debris is still
Burning Garbage
   Burning garbage in open dumps and in the
    incinerators of apartment buildings and hospitals
    was used at one time. Because burning
    releases harmful gases, the practice is being
    halted. Sometimes the old incinerators are
    replaced with highly efficient incinerators. Some
    buildings use waste to energy incinerators. The
    heat produced is used to convert water into
    steam which is then used to generate electricity
    or heat the building.
Recycling Solid Waste
   Most environmentalists prefer recycling.
    Recycling not only gets rid of solid waste
    but also creates useful materials.
Air Pollution
Air Pollution
   The most significant source of air pollution is
    motor vehicles. The air is made up of oxygen,
    nitrogen, carbon dioxide, and water vapor.
    When fossil fuels are burned, pollutants enter
    the air. The gasoline burned in the engines of
    automobiles contains hydrocarbons. Pollution
    occurs when the gasoline is not completely
    burned in the engine. Some hydrocarbons as
    well as carbon monoxide enter the air.
   Hydrocarbons, carbon monoxide and
    several other gases often react in sunlight
    to form a thick brownish haze called smog.
    Smog contains chemicals that irritate the
    eyes and make breathing difficult. Smog is
    very dangerous for people with asthma.
    Smog can also damage or kill plants.
    Smog can build up in a temperature
    inversion. This happens in Los Angeles.
Temperature Inversion
   A temperature inversion occurs when cool air
    near the Earth’s surface becomes trapped under
    a layer of warm air. Normally, cool air is heated
    by the Earth’s surface and rises, taking
    pollutants with it. But during a temperature
    inversion, the layer of warmer air acts as a lid
    and the pollutants are trapped in the cooler air
    near the surface. In the 1940’s some died and
    others were hospitalized in Donora, PA during a
    temperature inversion.
Acid Rain
   Factories and cars release many
    pollutants into the air. Some of these
    pollutants include sulfur and nitrogen
    compounds called oxides. In the
    atmosphere, sulfur oxides and nitrogen
    oxides combine with water vapor and form
    acids: sulfuric and nitric. These acids fall
    to Earth as precipitation known as acid
Problems with Acid Rain
   Very often acid rain falls many kilometers
    away from the original source of the
    pollution. Acid rain from factories in
    Germany, France and Great Britain killed
    fish and trees in Sweden. The best way to
    control acid rain is to burn low-sulfur coal
    but it is expensive.
Indoor Air Pollution
   Indoor pollution is a serious problem.
    Some appliances used in homes and
    offices give off potentially dangerous
    gases. In addition, often the houses are
    insulated in order to be energy efficient.
    Pollutants that might otherwise escape
    through cracks are trapped inside. One of
    the leading causes of indoor pollution is
Water Pollution
Water Pollution
   More and more of the water on Earth is
    becoming unusable. One reason for a
    shortage of water is water pollution.
    Obtaining and using energy resources are
    the major causes of water pollution.
Sources of Water Pollution
   Acid Rain
   Strip Mining
   Oil Spills
   Nuclear power
   Hazardous Wastes
   Sewage and Agricultural Runoff
Acid Rain
   When acid rain falls into lakes, rivers and
    streams, they increase the acidity level of
    the water. Most fishes and other
    organisms that live in water can survive in
    only a narrow range of acidity. Acid rain
    kills many of the organisms living in the
Strip Mining
   Strip mining for coal releases pollutants
    that may run off into lakes and streams or
    may seep in to the soil to contaminate
Oil Spills
   Petroleum is often found under the ocean
    floor. To obtain this petroleum, offshore
    oil wells are constructed. Drilling accidents
    occurs and large amounts of oil spill into
    the oceans. Oil spills also occur when
    tanker carrying oil are damaged. Tankers
    also deliberately flush waste oil into the
    ocean. Plants and animals are killed.
Nuclear Power
   Water is needed to cool the reactors in
    nuclear power plants. Cold water from
    lakes and rivers is used for this process.
    As a result of this a lot of hot water is
    generated. This heated water is then
    discharged in to lakes. This causes the
    temperature to rise. This temperature
    increase is called thermal pollution since
    organisms die when temperatures rise.
Radioactive Wastes
   Radioactive wastes can also be a sources
    of ling-term water pollution. Radioactive
    wastes stored in underground containers
    may leak and pollute groundwater.
    Pollution of the oceans occurs if these
    wastes are dumped in the ocean.
Hazardous Wastes
   Prior to the 1970’s many industries
    dumped chemicals and other hazardous
    wastes directly into streams and other
    nearby bodies of water. Today they are
    not deposited directly into water, instead
    they are buried. Often leaks occur and the
    groundwater is polluted. Illegal dumping,
    called midnight dumping, also occurs.
   The greatest threat to human health
    comes form sewage. Sewage is the
    waste material that is carried away by
    sewers and drains. Sometimes it is
    dumped directly into streams. This
    sewage often contains disease-causing
    bacteria and viruses. Drinking water may
    become contaminated.
Danger to Fish
   Fish living in polluted water are also unfit
    for human consumption. Untreated
    sewage is also harmful to the fish and
    other organisms that live in the water.
    Bacteria in the water break down the
    sewage. In the process, the bacteria use
    oxygen. If too much oxygen is used, fish
    and other organism may die from lack of
Agricultural Runoff
   The runoff of agricultural wastes and
    chemicals from farmlands also contributes
    to water pollution. Chemicals such as
    Phosphates and nitrates are used in
    fertilizers to improve the growth of crops.
    When fertilizers run off the land in to a
    lake, they stimulate the growth of algae.
    The algae then use up the oxygen in the
    lake. Pesticides also enter the water.
What Can Be Done About
   Pollution can be reduced by conserving
    energy, by finding cleaner ways to use
    energy, and by making sure that wastes
    are disposed of in the safest possible
   Conservation is the wise use of natural
    resources so that they will not used up too
    quickly or used in a way that will damage
    the environment. The environment
    benefits two ways. First, nonrenewable
    resources last longer. Second, pollution is
Examples of Conservation
   Recycling
   Carpooling
   Public Transportation
   Turning down the thermostat in the winter
    and turning up in the summer
   Insulate homes
   Use less water
New Technologies
   New technologies can reduce pollution by
    creating cleaner and more efficient ways
    of obtaining and using energy resources.
    Technology can also help develop
    alternatives to fossil fuels.
Scrubber Systems
   The burning of coal has been made less
    damaging to the environment by the use
    of scrubber systems. A scrubber system
    works like a shower. As sulfur oxides are
    released from burning coal, a high-
    pressure spray of water dissolves the
    oxides before they can react with the
    water vapor. They can be used on
Oil Drilling and Spills
   New methods have been used to drill for
    oil under the ocean floor in order to reduce
    underwater leaks. Several new methods
    have been developed for cleaning up oil
    spills with vacuum systems. Oil-eating
    bacteria have also been developed.
Waste Disposal
   Hazardous waste should be separated
    from industrial waste.
   Hazardous waste should be reused or
    recycled when possible.
   The waste should be treated chemically to
    destroy the toxic materials they contain.
   The wastes should be buried in landfills
    with many safeguards to prevent leaks.
Everyone’s Responsibility
   Pollution is mainly caused by the activities
    of people. It is important to realize that the
    activities of people can also reduce
    pollution. Everyone can help!

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